Broniatowski M, Vito K J, Shah B, Shields R W, Strome M
Department of Otolaryngology and Communicative Disorders, Cleveland Clinic Foundation, Ohio, USA.
Dysphagia. 1997 Spring;12(2):93-7. doi: 10.1007/PL00009525.
Laryngeal adduction for swallowing chiefly involves contraction of the thyroarytenoid and lateral cricoarytenoid muscles to seal the glottic chink. Vocal cord elongation supplements closure through cricoarytenoid activation. Relaxation of the posterior cricoarytenoid muscle is also involved in the swallowing process. Recent interest has focused on stimulating the laryngeal nerves to protect the lower airway from conditions where normal muscular coordination may be disrupted (e.g., in aspiration following stroke). Unfortunately, electrical stimulation results in a generalized contraction of all the dependent intrinsic laryngeal muscles because the larger, more excitable axons fire before their smaller counterparts can be activated. In the physiological state, however, the smaller fibers are recruited first. The current study focuses on electronic manipulation of force in the glottic muscles involved in deglutition. We used a stimulator that could selectively activate the intrinsic laryngeal muscles based on their specific motor unit architectures. In 5 dogs, the circuit recruited the axons in the recurrent and superior laryngeal nerves from small to large. The muscles were identified according to the differential recruitment rates of their compound muscle action potentials as they appeared on the graph. The smaller axons in the thyroarytenoid recruited faster than the large ones found in the lateral cricoarytenoid muscles, with intermediate figures observed with the cricothyroid. The posterior cricoarytenoid presented with the slowest recruitment rates, as expected from this muscle's highest contingent of larger motor units. Latencies between the onsets of stimulations and muscle saturations also appeared stable. This approach to manipulating glottic force saves energy because it allows stimulating the adductory muscles with minimal interference from their abductor antagonist.
吞咽时的喉内收主要涉及甲杓肌和环杓侧肌收缩以封闭声门裂。声带延长通过环杓肌激活辅助封闭。环杓后肌的松弛也参与吞咽过程。最近的研究兴趣集中在刺激喉神经以保护下呼吸道免受正常肌肉协调可能被破坏的情况（例如中风后的误吸）影响。不幸的是，电刺激会导致所有依赖的喉内肌普遍收缩，因为较大、更易兴奋的轴突比较小的轴突先放电。然而，在生理状态下，较小的纤维首先被募集。当前研究聚焦于对吞咽时参与的声门肌力量进行电子操控。我们使用了一种刺激器，它可以根据特定运动单位结构选择性激活喉内肌。在5只狗身上，该电路按从小到大的顺序募集喉返神经和喉上神经中的轴突。根据复合肌肉动作电位在图表上出现时的不同募集率来识别肌肉。甲杓肌中的较小轴突比较大环杓侧肌中的轴突募集得更快，环甲肌则介于两者之间。正如预期的那样，环杓后肌的募集率最慢，因为该肌肉中较大运动单位的比例最高。刺激开始与肌肉饱和之间的潜伏期也似乎稳定。这种操控声门力量的方法节省了能量，因为它允许以最小程度受到外展拮抗肌干扰的方式刺激内收肌。
